Battery Glossary – Terminals

Terminals –  these are the electrical contacts on the battery where you would connect your electrical device / charger. All batteries have two terminals:

• Positive terminal – the terminal toward which electrons flow when connected to an device. Usually marked by the symbol ‘+’ and/or the color red.
• Negative terminal – the terminal from which electrons flow when connected to an device. Usually marked by the symbol ‘-‘ and/or the color black.

There are many terminal types to choose from based on the model and manufacturer of the battery or the electrical device that will be connected.  The most popular are:

Post Terminals

One of the most common terminal structures due to their use in the automotive industry. Terminal posts allow for strong, substantial, vibration resistant connections to the battery where large surges in current need to be handled. Cranking batteries used to start gasoline and diesel engines are in this category because they provide heavy power for short periods.

However, post terminals can also be found on deep cycle batteries where manufacturers who also produce cranking batteries use them instead of creating extra costs through different terminal designs.

Nut and Bolt Terminals

Also popular in the automotive industry and used on a number of heavier duty sealed lead acid batteries where higher current surges may be experienced such as the high rate discharge that Uninterruptible Power Supplies (UPS) back up batteries might need to deliver.

The exact dimensions of the nut and bolt terminals vary by battery model.

F1 Faston Terminals

Found on smaller batteries and especially popular on sealed lead acid batteries that back up devices such as emergency lights, toys, fire alarms and smaller Uninterruptible Power Supplies (UPS). The wiring from the appliance ends in spade connections which slide onto the faston terminals.

Note: F1 faston terminals have specific dimensions at 0.8mm thick, 4.8mm wide and 6.35mm long and can appear in a variety of different locations on a battery, the image above is only one pair of possible locations.

F2 Faston Terminals

The heavier duty version of the F1 faston terminal due to its slightly larger size making it able to handle greater current flows. You’re more likely to find F2 fastons on batteries which backup  appliances such as UPS (Uninterruptible Power Supplies), especially batteries designed for ‘High Rate Discharge’.  Like the F1 it is often seen on sealed lead acid battery ranges.

Note: F2 faston terminals have specific dimensions at 0.8mm thick, 6.35mm wide and 7.8mm long and can appear in a variety of different locations on a battery, the image above is only one set of possible locations.

Wiring

Some batteries and battery packs have two wires coming out of the product rather than terminals. These usually require or have “connectors” in order to connect to devices they are designed for.